Discrete Simulation of Fluid Dynamics: methods
This Theme Issue collects specific contributions to methodological advances in Discrete Fluid Dynamics, i.e to capture the complexity of fluid flow behaviour by letting such complexity emerge naturally from the underlying micro-dynamics of appropriately simplified particle models. A substantial group of papers presents innovative developments of the LB method, targeted to a variety of subjects such as new types of boundary conditions, transport of passive and active scalars, thermodynamic consistency, improvements of the stability. Other advances are reported in the formulation of new LB models for Brownian suspensions and polymer flows, thermal fluctuations in multiphase flows, and hemodynamic flows with suspended biological bodies. As discrete simulation of fluid dynamics is much more than LB, besides advances in particle/grid computational fluid mechanics, such as particle-mesh methods on multicore GPU architectures, exciting developments in allied particle methods, typically Smoothed Particle Hydrodynamics (SPH), particle-mesh methods for fluid flows, as well as constrained Molecular Dynamics, are also reported. A new class of four dimensional (spacetime) variational algorithms to locate unstable periodic orbits of high-dimensional non-linear dynamical systems is described, which may disclose new avenues in computational studies of turbulence. The issue is addressed to physicists, mathematicians, engineers, computer scientists, and, in general, all scientists working in allied fields where fluids play a major role.

Discrete Simulation of Fluid Dynamics: applications
This Theme Issue provides the reader with a record of the state of the art in Discrete Fluid Dynamics, i.e. capturing the complexity of fluid flow behaviour by letting such complexity emerge naturally from the underlying micro-dynamics of appropriately simplified particle models. This volume is specifically devoted to the application of discrete simulation methodologies to a variety of fluid problems in science and engineering, such as turbulence, combustion, flow in porous media, suspensions of charged colloids, multiphase flows, soft-flowing systems, involving lamellar and glassy-like states with highly non-Newtonian rheology. The remarkably broad spectrum of applications reported herein bears testimony to the amazing versatility of discrete methods in addressing different applications across many scales of motion, from macroscopic turbulence, all the way down to micro and nanofluidics. Besides the Lattice Boltzmann method, new applications of allied particle methods, typically Dissipative Particle Dynamics (DPD) and Smoothed Particle Hydrodynamics (SPH), are reported. The issue is addressed to physicists, mathematicians, engineers, computer scientists, and, in general, all scientists working in allied fields where fluids play a major role.